Liquid transport head and liquid transport apparatus provided with the same

Abstract

A liquid transport apparatus includes a flow passage which has a liquid discharge port and which includes a first area and a second area formed on an inner wall to make contact with a liquid, the second area being adjacent to the first area in a flow direction of the liquid and having liquid repellence higher than that of the first area. When the pressurized liquid is supplied to the flow passage toward the liquid discharge port, then the liquid is incapable of passing through the second area owing to the liquid repellence of the second area, and thus a gas stays in the second area in accordance therewith. The liquid transport apparatus further includes a liquid passage-permitting mechanism which selectively permits the pressurized liquid to pass through the second area. The apparatus is provided, wherein the high integration can be easily realized, and the flow passage is simply constructed.

1. A liquid transport head comprising:
 a liquid passage-permitting mechanism; and 
 a flow passage which has a liquid discharge port and which includes a first area and a second area formed on an inner wall which makes contact with a liquid, the second area being adjacent to the first area in a flow direction of the liquid and having liquid repellence higher than that of the first area, wherein the liquid, which is pressurized to move toward the liquid discharge port, is incapable of passing through the second area to move toward the liquid discharge port, and thus a bubble clogs the flow passage in the second area until the liquid passage-permitting mechanism selectively permits the pressurized liquid to pass through the second area, 
 wherein the liquid passage-permitting mechanism includes:
 a first electrode which is formed at a position different from a position corresponding to the second area; 
 an insulator which is formed as an inner wall of the flow passage in the second area; and 
 a second electrode which is electrically connected to the insulator. 
 
 
     
     
       2. The liquid transport head according to  claim 1 , wherein a pressure, which is applied to the liquid, is varied. 
     
     
       3. The liquid transport head according to  claim 2 , wherein the liquid is an ink. 
     
     
       4. The liquid transport head according to  claim 2 , wherein the flow passage has a plurality of individual flow passages, and the liquid discharge port includes discharge ports which correspond to the plurality of individual flow passages and which are arranged to form an array. 
     
     
       5. The liquid transport head according to  claim 4 , further comprising a first common flow passage which is connected to an individual flow passage of the individual flow passages assigned by an ordinal number of (n×N+1), a second common flow passage which is connected to an individual flow passage assigned by an ordinal number of (n×N+2), . . . , and an nth common flow passage which is connected to an individual flow passage assigned by an ordinal number of (n×N+n) as counted from an individual flow passage disposed at an outermost end provided that n represents a fixed natural number of not less than 2, and N represents a variable integer of not less than 0, wherein n pieces of the common flow passages are formed at positions different in distance with respect to the associated individual flow passages respectively. 
     
     
       6. The liquid transport head according to  claim 5 , wherein the n pieces of the common flow passages are filled with inks which have different colors as the liquid respectively. 
     
     
       7. The liquid transport head according to  claim 4 , further comprising a common flow passage which is commonly connected to the plurality of individual flow passages. 
     
     
       8. The liquid transport head according to  claim 2 , wherein the flow passage has an atmospheric air communication hole which is formed at a position corresponding to the second area in the flow direction of the liquid. 
     
     
       9. A liquid transport apparatus comprising:
 a liquid transport head according to  claim 2 ; 
 a pressurizing mechanism which pressurizes a liquid in the liquid transport head in a direction directed toward the liquid discharge port; and 
 a control unit which controls the liquid transport head, 
 wherein the liquid passage-permitting mechanism selectively permits the pressurized liquid to pass through the second area on the basis of control of the control unit. 
 
     
     
       10. The liquid transport apparatus according to  claim 9 , wherein the pressurizing mechanism applies a varying pressure to the liquid in the liquid transport head. 
     
     
       11. The liquid transport apparatus according to  claim 9 , wherein the control unit is capable of adjusting a time to vibrate the inner wall of the flow passage. 
     
     
       12. The liquid transport apparatus according to  claim 9 , wherein the apparatus is an ink-jet printer which jets an ink. 
     
     
       13. The liquid transport head according to  claim 1 , wherein one or more bumps are formed at one or more positions corresponding to one or more edges of the second area in the flow direction of the liquid on the inner wall. 
     
     
       14. The liquid transport head according to  claim 13 , wherein the liquid is an ink. 
     
     
       15. The liquid transport head according to  claim 13 , wherein the flow passage has a plurality of individual flow passages, and the liquid discharge port includes discharge ports which correspond to the plurality of individual flow passages and which are arranged to form an array. 
     
     
       16. The liquid transport head according to  claim 15 , further comprising a first common flow passage which is connected to an individual flow passage of the individual flow passages assigned by an ordinal number of (n×N+1), a second common flow passage which is connected to an individual flow passage assigned by an ordinal number of (n×N+2), . . . , and an nth common flow passage which is connected to an individual flow passage assigned by an ordinal number of (n×N+n) as counted from an individual flow passage disposed at an outermost end provided that n represents a fixed natural number of not less than 2, and N represents a variable integer of not less than 0, wherein n pieces of the common flow passages are formed at positions different in distance with respect to the associated individual flow passages respectively. 
     
     
       17. The liquid transport head according to  claim 16 , wherein the n pieces of the common flow passages are filled with inks which have different colors as the liquid respectively. 
     
     
       18. The liquid transport head according to  claim 15 , further comprising a common flow passage which is commonly connected to the plurality of individual flow passages. 
     
     
       19. The liquid transport head according to  claim 13 , wherein the flow passage has an atmospheric air communication hole which is formed at a position corresponding to the second area in the flow direction of the liquid. 
     
     
       20. A liquid transport apparatus comprising:
 a liquid transport head according to  claim 13 ; 
 a pressurizing mechanism which pressurizes a liquid in the liquid transport head in a direction directed toward the liquid discharge port; and 
 a control unit which controls the liquid transport head, 
 wherein the liquid passage-permitting mechanism selectively permits the pressurized liquid to pass through the second area on the basis of control of the control unit. 
 
     
     
       21. The liquid transport apparatus according to  claim 20 , wherein the pressurizing mechanism applies a varying pressure to the liquid in the liquid transport head. 
     
     
       22. The liquid transport apparatus according to  claim 20 , wherein the control unit is capable of adjusting a time to retain the low liquid repellence member at the position at which the surface of the low liquid repellence member makes contact with the liquid in the flow passage. 
     
     
       23. The liquid transport apparatus according to  claim 20 , wherein the apparatus is an ink-jet printer which jets an ink. 
     
     
       24. The liquid transport head according to  claim 1 , wherein a surface of the second area, which makes contact with the liquid, protrudes as compared with a surface of the first area which makes contact with the liquid. 
     
     
       25. The liquid transport head according to  claim 1 , wherein the flow passage has an opening which is open to atmospheric air so that a cross section of the flow passage is formed to be recessed, and the opening extends in the flow direction of the liquid. 
     
     
       26. The liquid transport head according to  claim 25 , wherein an outer wall of the flow passage, with which the opening is formed, is formed to have liquid repellence which is higher than that of the first area. 
     
     
       27. The liquid transport head according to  claim 1 , wherein the liquid is an ink. 
     
     
       28. The liquid transport head according to  claim 1 , wherein the flow passage has a plurality of individual flow passages, and the liquid discharge port includes discharge ports which correspond to the plurality of individual flow passages and which are arranged to form an array. 
     
     
       29. The liquid transport head according to  claim 28 , further comprising a first common flow passage which is connected to an individual flow passage of the individual flow passages assigned by an ordinal number of (n×N+1), a second common flow passage which is connected to an individual flow passage assigned by an ordinal number of (n×N+2), . . . , and an nth common flow passage which is connected to an individual flow passage assigned by an ordinal number of (n×N+n) as counted from an individual flow passage disposed at an outermost end provided that n represents a fixed natural number of not less than 2, and N represents a variable integer of not less than 0, wherein n pieces of the common flow passages are formed at positions different in distance with respect to the associated individual flow passages respectively. 
     
     
       30. The liquid transport head according to  claim 29 , wherein the n pieces of the common flow passages are filled with inks which have different colors as the liquid respectively. 
     
     
       31. The liquid transport head according to  claim 28 , further comprising a common flow passage which is commonly connected to the plurality of individual flow passages. 
     
     
       32. The liquid transport head according to  claim 1 , wherein the first electrode is formed on a side opposite to the liquid discharge port with respect to the position corresponding to the second area. 
     
     
       33. The liquid transport head according to  claim 1 , wherein the first electrode is formed in the common flow passage. 
     
     
       34. The liquid transport head according to  claim 1 , wherein the flow passage has an atmospheric air communication hole which is formed at a position corresponding to the second area in the flow direction of the liquid. 
     
     
       35. A liquid transport apparatus comprising:
 a liquid transport head according to  claim 1 ; 
 a pressurizing mechanism which pressurizes a liquid in the liquid transport head in a direction directed toward the liquid discharge port; and 
 a control unit which controls the liquid transport head, wherein
 the liquid passage-permitting mechanism selectively permits the pressurized liquid to pass through the second area on the basis of control of the control unit. 
 
 
     
     
       36. The liquid transport apparatus according to  claim 35 , wherein the pressurizing mechanism applies a varying pressure to the liquid in the liquid transport head. 
     
     
       37. The liquid transport apparatus according to  claim 35 , wherein
 the control unit is capable of adjusting a time to apply a voltage between the first electrode and the second electrode. 
 
     
     
       38. The liquid transport apparatus according to  claim 35 , wherein the apparatus is an ink-jet printer which jets an ink. 
     
     
       39. A liquid transport apparatus comprising a liquid transport head according to  claim 1 ,
 wherein a liquid is conductive, and the liquid is permitted to pass through the second area from the first area depending on a voltage applied to the electrode. 
 
     
     
       40. The liquid transport apparatus according to  claim 39 , further comprising another electrode which makes contact with the liquid, wherein a liquid discharge port is connected to the first area.